furnace soot

[Pat]

My neighbors seem to be getting soot from their RV furnace.? The inside of the burn chamber and parts in there look clean.? Would dirty propane be a possible culprit?? I mentioned the blue flame, and he said it looks OK.

They don't have internet access, so I recommended asking here for some experience.

--pat

 

[Pat]

Printed a helpful article from the CampingWorld website that explains something about furnace soot.  "Improper mixture" it says.  The Suburban website says it's a serious fire hazard.  I think they're switching to a space heater until they get it serviced.

--pat

 

[bajadudes]

Improper mixture is almost always the culprit.  The most common cause is a partially blocked air intake causing the mixture to be to rich IE: not enough oxygen.  This almost always coincides with the first few times you fire it up after it has been sitting out the warm weather.  Look for a wasps nest in the intake or some other such insect nuisance in there.

 

[Gary RV_Wizard]

bajadudes has it right - that is almost certainly the problem.

 

[Pat]

Thanks for the feedback.? I'm forwarding and saving.

Neighbors had recently had a connector installed and were using a rented, larger capacity propane tank.? Apparently when they turned off the new tank and went back to using their onboard tank last night, the soot and smoke problem seemed to have abated.? ? Problem with the onboard tank is, of course, that they have to move every week or so to fill it.?


--pat

 

[Shayne]

Why don't they jkust make arrangements with a Propane co., to come fill it on designated days. This is an occurrance I've seen throughout the country for many years. 

 

[Gottasmilealot]

An improperly adjusted flame, or an incorrect part, will do it.? Regardless of the cause, you should never get soot from the combustion in the ducted air being circulated in your RV.? The products from a combustion problem should go out the exhaust, flue/chimney. Soot in your ducts is a sign of a defective heat exchanger which can be dangerous because carbon monoxide can be circulated through the ductwork rather than being exhausted. That is how a furnace eventually fails.? The heat exchanger rusts through.? A qualified service person can confirm the integrity of the heat exchanger for you.

If what you're getting is dirt or dust, then check your air filter.? If they get dirty, they'll suck in and be bypassed.

If the soot is only showing at the furnace vent outside, and it disappears with the change in propane supply as indicated, then obviously it looks like the propane supply is suspect. It's possible to get dirty propane which is caused by the supplier using a bad or worn compressor that permits lube oil to get into the gas, which gets burnt off, causing the soot.  You should have the people mention the problem to whoever sold them the gas in the tank that's causing the problem.

 

[Pat]

Sounds dangerous.  They have a service call in to check everything. The soot looked to me like a very lightweight, cottony grey dust. 

Most of these motorhomes have CO alarms.  Theirs hasn't been triggered so far.  However, they have two cats, and small animals are more susceptible to a lot less gas.   

In some places onsite propane refills are not legal.  I think one of the problems with RV parks is accessibility to onboard tank.  These spots are small.

--pat

 

[Gottasmilealot]

Cottony grey dust sounds like they need the air filter checked if they have one. Maybe a filter was removed and never replaced?  Just a thought.

 

[John From Detroit]

One possibility I have not seen discussed ANYWHERE is that propane is not always propane,  Sometimes they mix in a less expensive gas .  I'm wondering if the air-fuel ratios are the same for both gasses and thus if you need adjustment as you go from one to the other

Now, understand I've the books and science to figure it out,  What I lack is sufficient motivation.

 

[Pat]

Something interesting the local propane guy told them:  We have had nonstop rain, and it tends to cause soot and ash from the propane appliances.  I am having this furnace checked, probably Wednesday.  It's never been adjusted or professionally cleaned.  The soot in here is not bad, but there is some.  It's easy to confuse with dust and cat fur.  I vacuum at least once a day.  Always blamed the cat for the dust. 

Stovetop burners look fine.  Blue flame.  Maybe a touch of yellow in one of them, but that could have been burning dust, since I never use the stovetop. 

I was thinking this lifestyle is potentially too expensive and too overwhelming for my repair skills, but maybe I'll stick out the winter.  I'm cat sitting in a place that is not nearly as well made.

--pat

 

[John From Detroit]

Ok Soot INSIDE the motor home is another matter,  It is most likely dust and cat hair that has been sucked or drifted into the heat exchanger when it was non-operational and charred when you fired that sucker up.

HOWEVER, it might not be

And that is where having a professional look at it helps.

The burner should exhaust OUTSIDE the motor home and thus any soot from combustion should be OUTSIDE the motor home

If, however, the heat exchanger has rusted out, then there is a hole in between the burner and the blower... You can fail to wake up in the morning.  (Early symptoms include headache by the way)

Last summer I had them tear out my very old furnace (40-65 years) and replace it with a brand new furnace/Air conditioner (House, not motor home) figuring it will benefit come sales time.

Found out it will benefit more... While the old unit was lying on the driveway awaiting the scrap metal guy I took a good look at the holes in the heat exchanger and said "Just in time"

That puppy was about to kill someone... ME!

 

[Pat]

I definitely hear, feel, and smell the exhaust outside the mh, and there are no visible obstructions as far in as the flashlight reaches into the intake or exhaust.  There are a couple grey stripes running down from the exhaust.  I had them once before a couple years ago.  I think it's fine, but I'll be glad to get the technician to check it out.  I'm looking forward to learning about it. 

Question:  Is it typical to have to reset the mixture at each location due to weather or other local conditions?

I ran into another neighbor who has had soot and learned about the rain affect from a friend long ago. 

No headaches so far.  Cat seems oblivious.  No alarms.  I have LP, CO, and smoke.   

This furnace has been used about three years.  It's so much more comfortable than the heat pump or a space heater.


--pat